class A {
	final double PI=3.1415926;// PI是常量
	public double getArea(final double r) {
		//r = r+1; 非法，不允许对final变量进行更新操作
		return PI*r*r;
	}
	public final void speak() {
		System.out.println("您好，How's everything here ?");
	}
}
public class Example5_9 {
	public static void main(String args[]) {
		A a=new A();
		System.out.println("面积："+a.getArea(100));
		a.speak();     
	}
}
